Linux Kernel: UAF in Tracing Histogram via event_file misuse
CVE-2026-99235 Published on November 2, 2026
tracing: Save the event file instead of the compatible histogram
In the Linux kernel, the following vulnerability has been resolved:
tracing: Save the event file instead of the compatible histogram
create_field_var_hist() creates a histogram on the matched event to
supply a field variable, and records it on the target so it can be torn
down later:
hist_data = find_compatible_hist(target_hist_data, file);
...
/* Save the compatible histogram information */
var_hist->hist_data = hist_data;
hist_data is not the histogram it creates. It is one that was already
there, whose keys the new one copies. The saved pointer has a single
user, unregister_field_var_hists(), which runs when the target is
removed:
file = hist_data->field_var_hists[i]->hist_data->event_file;
find_compatible_hist() matches on keys alone, so it can pick one with no
variables of its own. check_var_refs() then returns false and the user
can remove it while the target still points at it:
BUG: KASAN: slab-use-after-free in event_hist_trigger_free+0x2b2/0x320
Read of size 8 at addr ffff8880093b90e0 by task init/1
Freed by task 1:
kfree+0x154/0x420
event_hist_trigger_free+0x1d5/0x320
event_hist_trigger_parse+0x35f3/0x69e0
trigger_process_regex+0x1a6/0x250
Save the event file instead. It is all the dereference ever wanted, and
it does not go away when the user removes a trigger.
Products Associated with CVE-2026-99235
Want to know whenever a new CVE is published for Linux Kernel? stack.watch will email you.
Affected Versions
Linux:- Version 02205a6752f223779a1b0e9e8ffacbea6e717851 and below a6165126b1a1b26342b55be6eb6ee23af8756aba is affected.
- Version 02205a6752f223779a1b0e9e8ffacbea6e717851 and below 173914501b97236d7ea7dc2af7f30feddd4e1436 is affected.
- Version 02205a6752f223779a1b0e9e8ffacbea6e717851 and below ac815a379644b2ad5008a009a3516ada31b5dd82 is affected.
- Version 02205a6752f223779a1b0e9e8ffacbea6e717851 and below 8b307d64a60548e4a74cb746f74d7ed4bd49965e is affected.
- Version 02205a6752f223779a1b0e9e8ffacbea6e717851 and below 7a111ba0d1b74c99bc8f096565dc71945f694254 is affected.
- Version 02205a6752f223779a1b0e9e8ffacbea6e717851 and below 3609ada3c12cecfb0ae5ee82ef4f86c5f18a2dea is affected.
- Version 02205a6752f223779a1b0e9e8ffacbea6e717851 and below 9631dbccd3c649b567a5aafffea6b00634183997 is affected.
- Version 02205a6752f223779a1b0e9e8ffacbea6e717851 and below 7cafc82e6153f05a221be678cd649d02e06ba909 is affected.
- Version 4.17 is affected.
- Before 4.17 is unaffected.
- Version 5.10.273, <= 5.10.* is unaffected.
- Version 5.15.224, <= 5.15.* is unaffected.
- Version 6.1.191, <= 6.1.* is unaffected.
- Version 6.6.161, <= 6.6.* is unaffected.
- Version 6.12.115, <= 6.12.* is unaffected.
- Version 6.18.60, <= 6.18.* is unaffected.
- Version 7.2.14, <= 7.2.* is unaffected.
- Version 7.3.1, <= 7.3.* is unaffected.